This application claims the priority of Swiss Application No. 2000 1132/00 filed Jun. 8, 2000, which is incorporated herein by reference.
This invention relates to a gripper apparatus for grasping articles and is of the type which includes a basic suction body to which vacuum is applied and which is provided with a suction opening to be aligned with a surface of the article to be grasped and further includes a vacuum source coupled to the basic suction body.
A gripper of the above-outlined type, as described, for example, in German patent document 39 06 634, can simultaneously pick up a plurality of items with a plurality of suction heads. This apparatus, however, is not capable of picking up with one suction head simultaneously or consecutively several items for forming an item group.
European Patent No. 0 532 774, to which corresponds U.S. Pat. No. 5,263,753, describes a further gripping apparatus in which the suction opening has four circumferentially arranged gripping arms and which, by exposing a diaphragm coupled thereto with vacuum, swing towards the item to be grasped and capture the same in a centered manner. A plurality of items cannot be simultaneously grasped with such a gripper.
U.S. Pat. No. 5,457,933 describes a gripping apparatus for grasping fruit. The apparatus includes a matrix of suction grippers which simultaneously grasp fruits arranged in a pattern and deposit the same at another location. The items are arranged side-by-side in rows and are grasped by a plurality of grippers.
Further, U.S. Pat. No. 3,368,324 describes a gripping apparatus for baked goods. The apparatus is particularly designed for handling items having a delicate upper, not necessarily planar, product surface to be grasped by the suction gripper.
It is an object of the invention to provide an improved gripper apparatus of the above-outlined type which grasps the articles in a gentler manner while permitting an accelerated packing rate. In particular, it is an object of the invention to form a group of articles such as edible wafers (for example, flat confectionary items) and to increase the packing speed in this manner without relinquishing a gentle handling of the items.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the suction gripper for lifting, transporting and depositing items includes a basic suction body having an inner surface; a first opening for coupling the basic suction body to a suction source; and a second opening through which an item is introduced into the basic suction body by suction. An abutment member is positioned within the basic suction body between the first and second openings such that a clearance is defined between the abutment member and the inner surface of the basic suction body for allowing a suction stream to pass from the second opening through the clearance into the first opening. A storage chamber is defined between the inner surface of the basic suction body, the second opening and the abutment member for accommodating an item drawn thereinto and held against the abutment member by suction.
By providing that the basic suction body has a height which is greater than the article to be grasped, an item group may be directly formed in the storage chamber.
A method for using a gripping apparatus of the above-outlined construction according to the invention includes the steps of picking up sequentially a plurality of items by the gripper apparatus and while vacuum is continuously applied in the basic suction body of the gripping apparatus, the items are intermediately stored. The temporarily stored item groups are subsequently deposited onto or into a device which moves away the grouped items.
Thus, since first a number of items are picked up from the supply conveyor and are then deposited as a group on the removing conveyor or in a package, the displacement paths are significantly reduced, and consequently the apparatus may operate more rapidly and more efficiently.
The items handled by the gripper apparatus according to the invention may be, in particular, wafer-shaped items, such as baked products like biscuits, frozen dough pieces, muffins, madeleines or similar products.